Grinding machine



June 4, 1935. RITZ, JR

GRINDING MACHINE Filed April 11, 1950 2 Sheets-Sheet 1 INVENTOR.Mfldg,94.

QMZW ATTORNEYS June 4, 1935. E, RlTZ, JR 2,003,495

GRINDING MACHINE 2 Sheets-Sheet 2 Filed April 11, 1950 ATTORNEY-9Patented June 4, 1935 UNITED STATES PATENT OFFICE GRINDING MACHINEApplication April 11, 1930, Serial No. 443,400

15 Claims.

My invention has to do primarily with driving means for grindingmachines, and one of its very important applications is to the drives ofhigh speed grinders which involve special problems.

In modern high speed grinding, the feature of importance is a certainperipheral speed of the grinding wheel. If a slower speed is employed,then the grinding is inemcient, whereas if the optimum speed is verymuch exceeded there is danger of the wheel exploding. Since peripheralspeed of a grinding wheel is not alone a function of the speed ofrotation of the shaft to which it is attached, but also has to do withthe diameter of the grinding wheel itself, and since due to wear )5 thediameters of the grinding wheels are continually changing, it isnecessary for satisfactory commercial operation to provide means forvarying the speed of wheels in these grinders.

An object of my invention, therefore, is to provide means forcontrolling and varying the speed in grinding machines. Since for agiven wheel diameter the speed should not be increased for safetys Sakebeyond a given point, it is another object of my invention to provide ina grinding machine safety means in connection with the speed changemeans, whereby too great a speed for any given diameter of grinder wheelis prevented. It is thus also my object to prevent a change of speed ingrinding machines when the diameter of the grinding wheel is too largeto render such speed change safe. Again, because, as hereinabove pointedout, it is necessary to have the grinding wheels at a certain optimumperipheral speed of which the shaft speed and wheel diameter arefunctions, in order to attain the utmost efiiciency, it is advisable toregulate the shaft speed very closely to the wheel diameter. A furtherobject of my invention therefore is to provide means for regulating theshaft speed very closely in accordance with the wheel diameter. Stillanother object of my invention is the provision of means to make suchspeed regulation substantially compulsory on thepart of the operator.

These and other objects of my invention which will be set forthhereinafter or will be apparent to one skilled in the art upon readingthese spec ifications, I accomplish by that certain construction andarrangement of parts of which I shall now describe a preferredembodiment, reference being had to the drawings which form a parthereof.

In the drawings:

Figure l is an elevation of a single drive shaft grinding machineembodying my invention.

Figure 2 is a section therethrough along the lines AA.

Figure 3 is an elevation of a two-shaft grinder equipped with separatedrives.

Figure 4 is a section of Figure 3 along the lines 5 BB.

In solving the problems to which my invention is addressed, I haveselected as most preferable a type of drive which permits a gradualchange of speed as contrasted with a change of speed by stages. Myinvention is, however, applicable to other types of drives, and is notrestricted to gradual change speed mechanism. In a grinding machine, Iprovide driving means and a change speed'mechanism connecting thedriving means and the driven shaft. Grinding wheels are mounted on theshaft, and these grinding wheels have the ordinary movable guards. Asthe diameter of the grinding wheel decreases with use, it is not onlypossible but necessary to move the guards back so that the surface ofthe wheel may be got at adequately. I couple the actuating devices of mychange speed mechanism in the preferred embodiment of my invention tomeans for moving the guards. Thus as theguards are moved back, the speedmay be changed; but so long as the diameter of the wheel prevents themovement of the guard, the speed may not be changed, thus eliminatingthe possibility of the speed of the driven shaft being increased to adangerous degree, while the wheel itself remains too large to'permit ofsucha speed change. Seeondly, however, since for effective grinding theguards must be moved back as the wheel grows smaller, my coupling of theguard moving means and the change speed operating means enforces aspeeding up of the machine as the wheel diminishes in size, thus keepingthe grinder always operating at maximum efliciency.

Referringnow to Figure 1, I have shown a grinding machine of standarddesign having 'a frame or housing I upon which a driven shaft 2 issupported in suitable bearings 3. This shaft, in standard grinders,bears a grinding wheel 4 at either end thereof. Guards 5 surround eachwheel, and are mounted so that they may be slid horizontally toward therear of the machine as the wheel size diminishes, thus enabling the workto be brought into proper relationship with the wheel. To this end, inthe form of grinderillus- 50 trated, the guards have brackets 6 whichare held to the tops of the bearing housings by bolts, and the bracketsare slotted where the bolts pass through to permit the horizontal motiondesired. Instead of the bolt I a hand-bolt la, such as constant.

shown in Figure 3 or, some other fastening device may be used, sincewhen the position of the guard has been adjusted, it is advisable totighten the guard-holding brackets to. prevent the unintended movementthereof.

While my invention is not restricted to the particular type of drivewhich I shall now describe, I have found this type completelysatisfactory. The type chosen comprises for a driving member opposedtapered or conical pulley members, the distance between which may bevaried. A relatively stiff belt or equivalent member having sidewiseinclined bearing surfaces engages between the two conical members. Asthese members are brought further apart, the belt rides closer to theshaft upon which they are mounted, thus varying the effective diameterof the driving means. Conversely as the conical members are caused toapproach, the effective diameter of the driving means becomes larger,because the belt rides further out on the conical surfaces of thedriving member. The driven member may also comprise a similar pair ofmembers having conical surfaces, and there may be interconnecting leverswhereby the distance between the conical members upon the driving anddriven shafts may be conversely varied. When this is done the distancebetween the axis of the drive and driven shafts remains It is moreeconomical however, and in some respects preferable, to use but onevariable diameter drive or driven member, but in this case the distancebetween the axes of the shafts must be varied. I shall describe a driveof the latter type. I provide, in the casing of my grinder, a base 8which is dove-tailed, and which has a secondary base 8a also dove-tailedand arranged to slide with reference to the main base 8 in a directiontransverse of the axis of the driven shaft. Upon this supplementary baseI mount a motor 9 having a driving shaft ID. A pair of opposed conicalmembers H and I2 are mounted on this shaft, the first one fixedly, andthe second longitudinally slidable on the shaft by reason of a collar I3to which it is attached, but nonrotatable with respect to the shaftbecause the collar is keyed to the shaft, as will be readily understood.The conical member I2 is urged toward the conical member H by a coiledspring M which surrounds the collar and bears against the member l2 atone end, and at the other against an abutment l5 fastened on the end ofthe shaft. The grinder or driven shaft 2 bears a pulley l6; and a beltmember I! of the type described, engages over the pulley I6 and betweenthe conical members H and I2. It will now be clear that as the distancebetween the axis of shafts 2 and I0 is increased, the driven speed ofshaft 2 will be decreased because the effective driving diameter ofparts I I and I2 will be decreased. The converse is also true. The frameof the grinder illustrated in the several figures is wide enough at thebase to permit a sufficient horizontal movement of the motor. As thedistance between shafts 2 and I0 increases, the belt I1, remainingconstant, will effect a separation of the driving members H and I2against the tension of the coiled spring [4, as will be readilyunderstood. To effect this horizontal motion of my motor, I mount athreaded shaft l8 in suitable supports IS on the base 8 so that it isrotatable with reference thereto, but is incapable of longitudinalmovement. This threaded shaft passes through a suitable hole in thedove-tailed portion of the supplementary base 811, which hole isthreaded to receive it. It will now be clear that a rotation of theshaft l8 will effect a horizontal movement of the motor 9 on itssupplementary base along the base 8, and will thus operate to change thespeed.

My guards 5 have operating members to effect their movement. Theseoperating members may take a wide variety of forms, two exemplary formsbeing shown by me. In Figures 1 and 2, lugs 2| on my guards haveextensions passing through slots 22 in the frame of the grinder. If thebolts I or other fasteningmembers la are released, it will be seen thatthe guards may be moved by means of these lugs, and to this end I bore ahole through the end of the lugs and thread it to receive a threadedshaft 23 mounted in the frame I upon suitable bearing supports 24, sothat it can rotate, but cannot be moved longitudinally. As the shaft 23rotates, the guard moves forward or back, depending upon the directionof rotation. I provide a similar structure for each guard, and haveindicated the structure on the righthand side of Figure 1 by numerals23a and 2 la, which designate parts corresponding to parts 2i and 23 onthe left part of Figure 1. Upon the threaded shafts 23 and 23a I mountrespective sprocket wheels 24 and 24a, and I interconnect these by achain or other suitable driving means 25 so that the shafts movetogetherand in the same direction, and thus the guards must be moved inunison. Both shafts preferably extend through the frame of the grinderand are fitted with handwheels 28 and 25a, by means of either of whichboth shafts may be operated.

The shaft 23, however, bears another sprocket 21 which is connected bymeans of a chain or other suitable driving means 28 to a sprocket 29'which is mounted upon a suitable shaft or stud 20' upon the base 8. Thesprocket 28 is non-rotatably connected by means of the shaft 30, orotherwise, to a gear 3! which meshes with a gear 32 on the threadedshaft 20.

The interconnection of the several parts will now be clear, and it willbe seen that as either of the handwheels 26 or 26a is rotated, bothshafts 23 and 23a rotate in the same direction, and the shaft 26 rotatesin an opposed direction. Thus as the guards are moved toward the rear inmy machine by the operation of shafts 23 and 23a, the motor is movedforwardly through the operation of shaft 29 in the opposite direction,and the speed of the grinder is thus increased. This will be clear fromFigure 2, in which it is shown how the effective diameterof the drivingmeans increases as the motor is moved forwardly. The

factor of safety is subserved because while the wheel diameter remainsconstant, the guards cannot be moved back, and consequently the speedratio cannot be changed. The factor of efiiciency is subserved becausewhen the wheel diameter has become substantially smaller, so that theperipheral speed of the wheel is no longer great enough for optimumresults, then the guards must be moved back in order that the work maybe brought up to the wheels; and the operation of I moving the'guardsback automatically effects the proper change of speed. It will beunderstood that the mechanical movements and driving means which I haveshown interconnecting the speed change actuating mechanism and the guardmoving mechanism may be varied without departing from the spirit of myinvention. It will also be clear for any given type of grinding work,wheel size and the like, the ratio of the parts in the motiontransmitting mechanism for effecting movement of the guards and changeof speed will be proportioned so that the proper speed for the then sizeof the wheel will be attained at each guard setting.

In the embodiment shown in Figures 1 and 2 th speed cannot be increasedimtil both wheels have been worn away to permit setting back of'righthand guard which is now free has been moved back. This will beapparent when it is considered that the speed may now be changed by amovement of the lefthand guard, and if the righthand guard is entirelyfree it may happen that the righthand wheel is too big when the changeof speed is effected to stand the increased speed. The righthand guardmay be interconnected with the lefthand guard so as to block the lattersrearward motion until the former shall also have been moved back, bymeans shown in Figure l of my copending application for Letters PatentNo. 409,400, filed Nov. 2,1929, and this may be done without departingfrom the spirit of my invention.

However, in single shaft grinders, if one wheel wears away very muchfaster than the other, it is advisable to replace this wheel withanother of the proper diameter, because even if the guard on this wheelis moved back without changing the speed of the grinder shaft, thesmaller grinding wheel will not be operating at maximum efficiencybecause its speed will be too low. Consequently, where it is not desiredto use large grinding wheels, and where different types of work are doneon each wheel of each machine, it is preferable to provide a two-shaftgrinder such as is illustrated in Figures 3 and 4, in which independentgrinding shafts 2a and 2b are mounted in suitable bearings, each havingits own motor 9a or 91) connected to it by a Variable speed drive as hashereinbefore been explained. To save room it may be necessary to ofisetthe motors in this type of machine by raising the base of motor 9a upona sub-base 8b. I have illustrated in the embodiment of Figures 3 and 4the same general construction excepting that now the moving means foreach guard is directly connected to the actuating means for changing thespeed of each drive, the drives being separated, and the handwheels 26band 260 not being interconnected. Because each grinder shaft has itsseparate prime mover, the speed of each may be directly changed inproportion to the allowable movement of its guard. In this embodimentthe guards are similarly mounted, but each has a rack bar 33 extendingthrough a slot 34 in the frame or housing, and meshing with a worm 35 onthe otherwise unthreaded shafts 36 and 36a of the handwheels 26b and26c. The direction of the spiral teeth on the worm 35 may be made suchthat as the guard moves back the motor 9a moves forward within thesprocket 31, and the shaft 36 is directly connected by means of chain 28to a sprocket 39 on the threaded shaft that moves the motorsupplementary base.

Various modifications may be made in my invention without departing fromthe spirit thereof.

Having thus described my invention, what I ent, is:

claim as new and desire to secureby Letters Pat- I. In a grindingmechanism or the like, a driven shaft, a motor, a variable speedtransmission interconnecting said motor and said-driven shaft, effectiveupon a variation of the distance between said motor and said shaft, agrinding wheel on said driven shaft, a guard surrounding said grindingwheel, and means simultaneously to move said guard and said motor.

2. In a grinding machine or the like, a driven shaft and a motor, saidmotor mounted for movement with respect to said shaft, and variablespeed transmission mechanism interconnecting said motor and said shaft,a grinding wheel on said shaft, a guard surrounding said grinding wheel,mechanical means for moving said guard, mechanical means for moving saidmotor, said last two mentioned means mechanically interconnected, andmeans for operating both simultaneously.

3. In a grinding machine, a housing and driven shaft in said housing, agrinding wheel on said driven shaft, a guard surrounding said grindingwheel and mounted slidably on said housing, a motor in said housingmounted for sliding therein, a variable change speed transmissioninterconnecting said motor and said shaft, a shaft arranged to move saidguard, a shaft arranged to move said motor and a mechanicalinterconnecthereto, a variable speed transmission interconmeeting saidmotor and said grind shaft, a shaft in said frame adapted to move saidmotor, a chain and sprocket connected between said guard movement shaftand said motor movement shaft whereby as said guard is moved back onsaid grinding wheel, the distance between said motor and said grindshaft will be decreased, and operating means upon one of said shafts.

5. In a grinding machine or the like, a housing, a grind shaft mountedin said housing, a grinding wheel on said shaft, a guard surroundingsaid grinding wheel and slidably mounted on said housing, said guardbearing a lug extended through a slot in said housing, a threaded shaftin said housing engaging said lug so as to move said guard, a base insaid housing and a supplementary base slidably mounted thereon, a motoron said supplementary base, a variable speed transmission mechanisminterconnecting said motor and said grind shaft, a threaded shaftmounted on said base and engaging said supplementary base so as to movesaid motor, and a chain and sprocket connection between said lastmentioned shaft and said shaft for moving said guard.

6. In a grinding machine or the like, a driving shaft, a driven shaft, adriven member on said driven shaft, pulleys on the respective shafts, abelt around said pulleys, one of said pulleys having a surface withwhich said belt may coact at various distances from the pulley axis,means yielding to hold the belt to coact with areas of said surface atthe various distances, and means movable for taking up the slack of thebelt, limited in its movement by said driven member.

7. In a grinding machine or the like, a driving shaft, a driven shaft, adriven member on said driven shaft, pulleys onthe'respective shafts, abelt around said pulleys, one of said pulleys having a surface withwhich said belt may coact at various distances from the pulley axis,means yielding to hold the belt to coact with areas of said surface atthe various distances, and means movable to vary the distances betweensaid shafts, limited in its movement by said driven member.

8. In a grinding machine or the like, a driving element, a drivenelement, an operative connection between said elements, means wherebythe ratio of speed transmission by said connection is varied by varyingthe distance between said elements, and means movable for varying saiddistance, limited in its movement by said driven member.

9. In combination with a grinding wheel, a motor movable toward and awayfrom said wheel, an operative connection from said motor to said wheel,having its ratio of transmission changed according to the distancebetween said wheel and said motor, and means movable to vary saiddistance, limited in its movement according to the diameter of saidwheel.

10. In a grinder the combination with a grinding wheel spindle and anelement overlying the periphery of a grinding wheel on said spindle andadjustable toward and away from said spindle, of a drive shaft, a changespeed driving connection between said spindle and shaft necessitatingrelative bodily movement between said spindle and shaft for changingspeed, a support carrying said drive shaft and adjustable for changingthe speed of said driving connection, means for locking said supportagainst movement to change to a higher speed and moveable to release thesame, and a connection between said adjustable element and said lockingmeans for operating said locking means to permit a change to a higherspeed with movement of said adjustable element toward said spindle. Y

11. In a machine of the character described, a grinding wheel, a motor,driving devices between said motor and wheel adapted to be altered tochange the speed of the wheel, said motor being bodily movable to andfrom said wheel to permit alteration of said devices for difierentspeeds, and stop means extending from the motor and co-operationg withthe periphery of the wheel so as to be regulated by the size of thewheel to control such movement of the motor.

12. In a machine of the character described, an insertable grindingwheel, a motor, driving devices between said motor and wheel adapted tobe altered to change the speed of the wheel, and stop means movable withthe motor for positively preventing the insertion of a wheel of givendiameter until such driving devices have been altered to impart properperipheral speed of said wheel.

13. In a machine of the character described, an insertable grindingwheel, a motor, driving devices between said motor and wheel adapted tobe altered to change the speed of the wheel, said motor being bodilymovable to and from the grinding wheel to permit alteration of saiddevices for different speeds, and means actuated by such movement of themotor to prevent the insertion of a wheel of given diameter until themotor has been moved to permit the alteration of the driving devicessuch as to impart a proper peripheral speed to said wheel.

14. In combination with a grinding wheel, a motor movable toward andaway from said wheel, an operative connection from said motor to saidwheel adapted to have its ratio of transmission changed merely byvarying the distance between said wheel and said motor, and meansmovable to vary said distance, limited in its movement according to thediameter of said wheel.

15. In combination with a grinding wheel, a motor movable toward andaway from said wheel, an operative connection from said motor to saidwheel adapted to have its ratio of transmission changed merely byvarying the distance between said wheel and motor, and stop meanscooperating with said wheel to limit the movement of the motor.

EMIL RITZ, JR.

